This invention relates to self-testing for the presence of glaucoma. In particular, it relates to a device and a method whereby one can detect the presence of glaucoma without the need of outside assistance.
Glaucoma is a prevalent afflication of the eye that can occur in anyone at any time and is a condition in which vision may become permanently lost. By far, the most common type of glaucoma is chronic simple glaucoma which is painless, slowly progressive and virtually undetectable by the individual particularly in its stages when it is most easily and sucessfully treated. Most individuals with glaucoma only become aware of it at a time when all that remains is tunnel vision due to its gradual, painless and progressive course when untreated.
With normal peripheral vision, at any given distance from the eye, a blind spot exists at a predetermined distance just temporal to a target point at which the eye is fixated. Most of the earliest scotomas in glaucoma (i.e., small circumscribed areas of dimness or actual loss of visual field) occur in a narrow region radiating generally arcuately from just outside this blind spot above and below the point of fixation. Advanced glaucoma changes are present when multiple scotomas in this region begin to coalesce after which they extend beyond the region itself and eventually encroach on or eliminate central vision.
Present visual testing for glaucoma requires sophisticated devices to accurately create a map, which is a graphic depiction of the extent of the field of vision, with any areas in which peripheral vision is diminished or absent well demarcated. These visual field tests require a technician to administer the test. The patient looks at a central fixation target and indicates when a light can be seen with side vision. These tests can be very accurate but they are often difficult to administer properly since they are tedious--often taking twenty minutes or more per eye--and it is difficult to completely prevent the patient from looking directly at the source of light which is the peripheral target rather than remaining fixed on a central target and using side vision to detect the light. One of these tests, the tangent screen, is a simple test, but it too has the same fixation problem and requires a technician.
It is therefore an object of the present invention to provide a procedure for detecting early glaucoma without the need of special equipment.
Still another object of the present invention is to develop a device for the self-determination of glaucoma which does not require a technician to perform the test.
Still another object of the present invention is to provide a simplified, low-cost, portable device for the determination of the presence of glaucoma.
Another object of the present invention is the development of a method and device for detecting glaucoma which can be used in the home, thus increasing the chances of early detection, long before one would normally become aware of and seek treatment for permanent glaucomatous vision loss.
Other objects and advantages of the present invention will become apparent from the ensuing description.